One of four British missionaries kidnapped in Nigeria three weeks ago has been killed, according to the Foreign Office, but the other three have been released.

Ian Squire was killed following the kidnap on October 14. However, David and Shirley Donovan and Alanna Carson have all returned home safely.

A statement from their families reported by the Daily Telegraph said: 'We are grateful for the support received by the British High Commission, and help from the Nigerian authorities in negotiating their release. We are delighted and relieved that Alanna, David and Shirley have returned home safely. Our thoughts are now with the family and friends of Ian as we come to terms with his sad death.'

The four were taken in a remote part of Delta state, where they were delivering aid to villages with a medical charity called New Foundations.

The area has a history of separatist movements and has suffered a spate of kidnappings recently linked to the central government's crackdown on Islamist milita.

Kidnapping for ransom is a common problem in parts of Nigeria and high-profile individuals and Westerners are often the target. A number of foreigners have, in the last few years, been kidnapped in the Niger Delta region, which holds most of the country's crude oil – the country's economic mainstay.

Chief Theo Fakama, from the local Enukorowa community, told the Agence France-Presse news agency that villagers were saddened by the kidnapping because the victims had 'brought succour to residents of the community for the past three years'.